When performing medical procedures using an intravascular ultrasound catheter, it is sometimes beneficial to move the catheter in a controlled manner in order to accurately characterize a lesion site. Characterization of the lesion site is performed using an ultrasound transducer mounted within the catheter, with the ultrasonic images being displayed using an external monitor which is part of the ultrasound system.
Movement of the ultrasound catheter through the lesion site is sometimes accomplished using a catheter displacement device also referred to as a "pull-back" device. A pull-back device is disclosed in U.S. Pat. No. 5,709,661, entitled "Electronic Catheter Displacement Sensor". The pull-back device can advance or retract a catheter slowly in a controlled manner through a desired location within a patient's vessel. In use, a physician advances the catheter to a site within the vessel that may be of interest and then uses the pull-back device to precisely move the catheter within the area of interest. A typical pull-back device being able to move the catheter in increments of 1.0 millimeters/second or less.
With advancements in intravascular ultrasound imaging, more precise characterizations of the lesion sites can be had, thereby increasing the ability for physicians to properly diagnose and treat a lesion site. These advancements require the precise movement and location of the catheter. Typical treatments to improvement the patency of the lesion site include the use of balloon angioplasty and when appropriate, the placement of a stent in the affected area.
A few problems currently exist when using a pullback device to control the movement of a catheter. One such problem is that currently there is no simple device which provides a relative position of the pull-back device to the introducer sheath or guide tube used to introduce the catheter into the patient. Not having such a device can affect the ability to properly determine how far a catheter has been advanced or retracted from a patient.
Another noted problem is that blood typically gets splattered over the pullback device during a procedure that may sometimes affect the operation of the device. A device, which could help redirect some of this blood away from the pullback device, would be beneficial. Additionally, in the use of a catheter without "over-the-wire" guidance, the guide wire may move from its intended fixed position in the vessel of interest while a pullback device controls the movement of a catheter. This of course could cause the physician to have to spend extra time placing the guide wire back into position during a procedure. As shown, a need exists in the art for a device that can minimize these noted problems.